ICD-11 Codes
for 4A00.00 - Neutrophil immunodeficiency syndrome

Teodor Jurukovski January 1, 1970

Fact checked by: Teodor Jurukovski

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Understanding neutrophil immunodeficiency syndrome

Neutrophil immunodeficiency syndrome is a rare primary immunodeficiency disorder classified under ICD-11 code 4A00.00. It is characterised by an elevated white blood cell count, specifically neutrophilia, combined with profound functional impairment of neutrophils.

Despite increased neutrophil numbers, these cells are unable to perform essential immune functions effectively. As a result, affected individuals are highly susceptible to bacterial infections and demonstrate impaired wound healing. A distinguishing clinical feature is the relative absence of pus formation at sites of infection, reflecting defective neutrophil migration and activity.

Alternative names for neutrophil immunodeficiency syndrome

Several alternative terms are used in specialist literature and diagnostic settings. Recognition of these synonyms supports accurate clinical documentation and interpretation of historical records.

Recognising the symptoms

Clinical manifestations typically begin in infancy or early childhood and are dominated by recurrent, severe infections. These infections may be bacterial or fungal and often involve multiple organ systems.

Rare associations with haematological malignancies, including certain forms of leukaemia, have been reported and warrant long term monitoring.

Genetic basis and pathophysiology

Neutrophil immunodeficiency syndrome is primarily caused by a dominant negative mutation in the RAC2 gene. This gene encodes Rac2, a small GTPase that plays a critical role in neutrophil signalling pathways.

Reduced Rac2 protein expression disrupts cytoskeletal organisation, impairing neutrophil shape change and motility. It also interferes with assembly and activation of the NADPH oxidase complex, which is essential for generating reactive oxygen species required to kill ingested microorganisms.

These combined defects result in neutrophils that circulate in high numbers but are functionally ineffective.

Diagnosis of neutrophil immunodeficiency syndrome

Diagnosis is based on a combination of clinical features, laboratory findings, and genetic confirmation. Early identification is important to reduce infection related morbidity.

Management and treatment strategies

Management focuses on reducing infection risk, treating active infections promptly, and correcting immune dysfunction where possible. Care is typically coordinated by specialist immunology and haematology teams.

Good skin and dental hygiene are essential supportive measures. Gene therapy is an area of ongoing research and may provide future therapeutic options for selected genetic neutrophil disorders.

Are neutrophil immunodeficiency syndrome ICD codes billable

Yes. ICD-11 code 4A00.00 is a billable diagnosis code when supported by appropriate clinical documentation and diagnostic evidence. Accurate recording of laboratory findings, genetic confirmation, and infection history is essential for correct coding, reporting, and reimbursement.